Today, the medical imaging community widely accepts Volume Rendering Technique (VRT) as a common way to visualize a volume. The Volume Rendering Technique renders a volume from the 2-dimensional tomography slices. Volume rendering is a technique used to display a 2D projection of a 3D discretely sampled data set. A typical 3D data set is a group of 2D slice images acquired by a Computer Tomography (CT) or Magnetic Resonance Imaging (MRI) scanner. Usually these are acquired in a regular pattern (e.g., one slice every millimeter) and usually have a regular number of image pixels in a regular pattern. An example, is a regular volumetric grid, with each volume element, or voxel represented by a single value that is obtained by sampling the immediate area surrounding the voxel. A voxel is a volume element, representing a value on a regular grid in a three dimensional space. This is analogous to a pixel, which represents 2D image data. Voxels are frequently used in the visualization and analysis of medical and scientific data. The Volume Rendering Technique application generally has imaging and visualization tools, which allow the radiologist or physician to mask/un-mask certain regions in the volume.
Generally various rendering techniques render different parts of the heart. Computer Tomography (CT), Magnetic Resonance Imaging (MRI), Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT) data could be used for rendering.
Rendering a fused image from plurality of other images from other modalities to the radiologist helps in more deep and precise diagnosis or treatment. Fused three dimensional representation or image of two separate datasets, for example one of Computed Tomography (CT) modality and one of Positron Emission Tomography (PET) modality, do exist. It is more or less an overlaying of one image over the other. The downside of this is that, its response time is very high during interaction and it also suffers from low picture quality.